Identification of changes in power through DC granular monitoring

In a competitive PV market, where different technologies are closing the gap in efficiencies at the module level, there is a need to reduce the cost of the overall PV system and its operation. This could be achieved either by reducing the cost of the installed PV system or reducing the long-term maintenance and operational cost of the array by cost effectively optimizing the performance of the PV system, thereby increasing the revenue from a PV array. To reduce the operational cost and maintenance, certain factors like soiling, module replacement and visual inspection needs to be carried out. For a large array of thousands of modules, maintaining a system at a regular basis is complicated. This could be achieved by investing upfront in a detailed monitoring of the system at a granular level. The level of granularity needs further attention which could offset the cost of operation and maintenance from a long term perspective. Understanding the module performance at an array, string, and module level has different resolutions on the information that can be obtained and individual module reliability is easier to be determined as the granularity becomes finer. The advantages and disadvantages of granular monitoring are discussed in this paper for four ~25kW photovoltaic arrays of three different technologies (c-Si, CIGS, and CdTe) deployed by the US Photovoltaic Manufacturing Consortium (PVMC).